页岩气藏“井工厂”模式下水平井裂缝分布优化

Optimization of fracture layout of fractured horizontal well in multi-well pad mode of shale gas reservoirs

与常规气藏单井开发模式相比,“井工厂”开发技术具有大幅提高作业效率、降低工程成本等优点。页岩气藏“井工厂”小井距布井以及体积压裂模式下存在井间干扰和缝间干扰,影响井组整体开发效果。基于非结构PEBI网格技术自主研发了压裂水平井PEBI网格模拟器,并以微地震监测结果为依据,将水平井组体积压裂形成增产改造体积区(SRV)(考虑为椭圆形),综合考虑了页岩气吸附解吸、扩散和非线性渗流机制,采用控制体有限单元法建立了均质页岩气藏“井工厂”模式定压生产条件下压裂水平井组数值模拟模型,计算对比了单井生产和井组生产累计产量的差异,讨论了均质页岩气藏井组不同压裂裂缝分布方式和水平井布井方式对井组累计产量的影响。研究结果表明:小井距布井产生的井间渗流干扰使得井组产量低于单井产量叠加之和;单井U型布缝模式能一定程度上减少干扰,使得其井组累计产量要优于均匀和反U型布缝模式;水平井交叉布井下累计产量要优于平行布井。

Compared with the single well development mode of the conventional gas reservoirs,multi-well pad technology has several advantages such as great improvement of operating efficiency and reduction of project cost.Strong interference between the wells and between the fractures exist in small well spacing and network fracturing mode of multi-well pad for shale reservoir,which affect the overall development effect of the well group.Based on the unstructured PEBI grid technology,its simulator for fracturing horizontal wells is developed independently.According to the results of microseismic monitoring,the stimulated reservoir volume(SRV)area formed by the network fracturing of horizontal well groups are assumed to be ovals.Considering the adsorption,desorption,diffusion and nonlinear seepage mechanisms of shale gas,the numerical simulation model of the fracturing horizontal well group in the multi-well pad mode is established by the finite element method.The difference between the cumulative production of the single well and the well group is compared,and the influence of the layout mode of the fractures and the horizontal wells on the cumulative production in homogeneous shale gas reservoirs are discussed.The results show that the interwell seepage interference makes the cumulative production of the well group lower than the sum of that of a single well.U-shape layout mode of the fractures for single well can reduce the interference to a certain extent,which make the cumulative production of the well group superior to that of the uniform mode and the inverted U-shape mode.The cumulative production of cross distribution of horizontal wells is better than that of parallel mode.